Process of preparing 8-amino-1-napththo-sulfonamides



naphthol monoor di-sulfonamide.

United States Patent PROCESS OF PREPARING S-AMINO-l-NAPTHTHO- SULFQNAMIDES William E. Wallace, Rensselaer, N.Y., assignor to General Aniline & Film Corporation, New York, N.Y.,

Claims. c1. zen-247.1)

The present invention relates to S-amino-l-naphtholsulfonamides and particularly to an improved process of amidating monoand di-sulfonic acids of 8-amino-1- naphthol.

In the preparation of S-amino-1-naphthol-3,6-disulfonamides from H-acid, it is the usual practice to first acylate the H-acid, then form the disulfonyl chloride, followed by amidation and hydrolysis. The yield of the sulfonam-ide ranges from 35 to 45%.

The protection of the amino group in the H-acid (by acylation) during conversion of the sulfonic acid to the sulfonyl chloride and then to the amide is a well known expedient. Phosgene is used to form carbamates as a protection for hydroxy groups. It is also known that the intermediary phosgenated compound from H-acid can be converted from the free di-acid to the di-sulfonyl chloride.

I have discovered that 8-amino-l-naphtholsulfonamides can be more economically produced, wherein the overall yield is at least 15% greater than heretofore obtained by first converting a monoor di-sulfonic acid of 8- amino-l-naphthol to the intermediary phosgenated reaction product for the purpose of protecting the amino group during conversion to the sulfonyl chloride followed by amidation and hydrolysis. In general the method consists of treating an aqueous alkaline slurry of a monoor di-sulfonic acid of 8-amino-1naphthol with phosgene in onder to form a carbamate which is treated with a sufficient quantity of chloro-sulfonic acid to produce the monoor di-sulfonyl chloride and the latter treated with an amine to form the amide, followed by hydrolysis to convert the carbamate derivative to the 8-amino-l- The unusual feature of this discovery is that the method can be used only With a specific class of monoand di-sulfonic acids of S-amino-l-naphthols disclosed herein.

Any S-amino-l-naphtholsulfonic acid whether containing 1 or 2 sulfonic acid groups and free from the other groups may be treated in accordance with the method of the present invention. As illustrative of such acids, the following are exemplary:

8-amino-1-naphthol-2-sulfonic acid S-amino-l-naphthol-3-sulfonic acid 8-amino-l-naphthol-S-sulfonic acid S-amino-l-naphthol-6-sulfonic acid 8-amino-1-naphthol-2,4-disulfonic acid 8-amino-1-naphthol-2,5-disulfonic acid 8 -amino1-naphthol-3,6-disulfonic acid 8-amino-1-naphthol-5,7-disulfonic acid 8-amino-1-naphthol-3,5-disultonic acid In carrying out the present invention, a concentration of 5-40% by weight of the monoor di-sulfonic acid of 8-amino-l-naphthol is slurried in water of sufiicient alkalinity to dissolve the acid, i.e. to form the monoor di-alkali salt, and an additional amount of caustic added to neutralize the hydrochloric acid formed by reaction of the phosgene with the amino naphthol; Phosgene 2,902,487, Patented Sept. 1, 1959 gas is passed into the solution at a low temperature, preferably between 0 and about 20 C. until a pH of about 4 is reached (Congo Violet). The charge may be heated if desired to 40-60 C. to drive off excess phosgene and to dissolve any solid which may be present, then cooled, whereupon crystals are formed which are filtered and dried. As noted above, any reasonable concentration of the monoor di-sulfonic acid of 8- amino-l-naphthol may be used, which includes the range of about 5% to about 40% by weight. The concentration depends to a great extent on the solubility in aqueous alkali of the compound being treated.

Subsequent treatment with chlorosulfonic acid may be carried out in any known manner of converting sulfonic acids to the monoor di-sulfonyl chlorides. I prefer however, to combine the intermediary phosgenated prod uct with chlorosulfonic acid at a temperature between 0-10 C. and then heating it and keeping it between 70-1 10 C. for a sufiicient period of time for the reaction to occur. This normally takes between 1-10 hours. The reaction mixture is then cooled to about room temperature and drowned in ice water so that the temperature of the drowning vessel is maintained at between 0-5 C., followed by filtering and washing. The resulting paste is treated with the minimum of at least two equivalent amounts per sulfonyl chloride group or up to about 250% excess, the excess being primarily to neutralize the acid, of a liquid organic amine or an aqueous or solvent solution thereof at a temperature between 5-30 C. and maintained thereat for a period of time ranging between l-24 hours, followed by filtering and sucking the product dry. A concentrated solution of amine is preferred, but may range from about a minimum of 30% up to 100% amine. Any compatible solvent which is inert under the conditions of amidation may be used, such as chlorobenzene, trichlorobenzerre, nitrobenzene, toluene, dioxane, carbontetrachlo-ride, ether and the like.

Amines which can be used include ammonia, monoand di-alkyl, aryl, aralkyl, cycloalkyl and saturated five and six membered nitrogenous heterocyclic amines, e.g. monoand dimethylamine, monoand di-ethylamine, monoand dipropylamine, hexylamine, octadecylamine, methyl ethyl amine, aniline, methylaniline, toluidine, benzylamine, monoand di-cyclohexylamine, morpholine, piperidine, pyrrolidine, etc. It is to be noted that any organic primary or secondary amine may be employed which does not contain substituents which will react with the sulfonyl chloride radical. The nature or character thereof is immaterial so long as it is in a liquid state.

The amidation reaction is accomplished by reacting the sulfonyl chloride derivative with the amine in liquid condition. If the amine is a liquid, the two components are mixed and allowed to stand for some time at a temperature below 30 C. The amine may also be employed as an aqueous solution or in a compatible organic solvent. In any case, the amine should be in liquid condition, the higher the concentration the better. Two equivalent amounts of amine or up to an excess of about 250% of amine per sulfonyl group may be used.

After amidation the resulting paste is treated by an alkaline hydrolysis. This may be accomplished by heating in an aqueous alkaline medium of caustic concentration in the range of 3-10% based on the weight of the solution to -100 C. for approximately 1 hour, cooled to 60-75 C. and diluted with water to give an approximate concentration of 2-15 A sufficient quantity of an acid or acid salt is added to the alkaline solution so as to reduce the pH between 7 and 9.5. The solution is cooled to a temperature between 0-5 C., filtered,

washed neutral with water and then dried. It is to be understood that any one of the known methods of hydrolysis may be employed.

The general overall reaction follows the equations;

. R H O /R (SOZN/ (SOZN alkali where n represents an integer ranging from 1 to 2 and R and R represent hydrogen, alkyl, e.g. methyl, ethyl, hexyl, octyl, octadecyl, etc., aryl, e.g. phenyl, tolyl, naphthyl, etc., aralkyl, e.g. benzyl, cycloalkyl, e.g. cyclohexyl, etc., and together R and R represent the atoms necessary to complete a 5 or 6 membered saturated heterocyclic radicle.

, The following examples, in which the parts are by weight unless otherwise indicated, are illustrative of the instant invention and are not to be regarded as limitative. Unless otherwise noted, the parts by weight are in grams and the parts by volume are in ccs.

Example I HzN (I) H 160 grams of S-amino-l-naphthol-3,6-disulfonic acid (I-I-acid) was slurried with 750 cc. water. Then 150 cc. 30% by Weight of sodium hydroxide was added. The temperature was reduced to below 10 C. and phosgene gas passed in until the solution became Congo Violet. A thick slurry was obtained which was maintained in workable condition by addition of a little water, up to a volume of about 1800 cc. It was heated to solution (about 50 C.), and cooled slowly, filtered and dried.

200 cc. of chlorosulfonic acid and 34.5 grams of the product obtained above were combined at a temperature below 10 C. and then heated and kept at 75 C. for 8 hours, cooled to C., and drowned in a mixture of ice and water so that the temperature in the drowning vessel is below 5 C. The product was filtered, washed with ice water and sucked dry. The resulting paste was added to 60 grams of a 70% aqueous ethylamine solution at a temperature below 15 C. It was maintained at this temperature for 4 hours, filtered and sucked dry.

The paste was added to a solution of 200 cc. of water and 50 cc. by weight of sodium hydroxide solution, heated to 95-100 C. for 1 hour, cooled to 70 C. and diluted to 500 cc. grams of sodium bicarbonate was added. It was cooled to 5 C., filtered, washed neutral and dried.

. 4 7 The above product is an excellent intermediate for the preparation of azo dyes.

Example 11 i Example I was repeated up through the formation of the sulfonyl chloride. This paste was added to 86.5 grams of aniline at room temperature and stirred for 4 hours. 50 grams of soda ash was added and the charge steam distilled until all aniline was removed. The resulting slurry was cooled, reduced to a pH of 7 with bydrochloric acid 20 B., cooled to about 5 C., filtered, washed and dried.

Example III E O NH;

grams of 8-amino-1-naphthol-5-sulfonic acid was slurried with 750 cc. of water. Then cc. 30% by weight of sodium hydroxide was added. The temperature was reduced to below 10 C. and phosgene gas passed in until the solution became Congo Violet. A thick slurry was obtained which was maintained in workable condition by addition of a little water, up to a volume of about 1800 cc. It was heated to solution (about 50 C.), and cooled slowly, filtered and dried.

200 cc. of chlorosulfonic acid and 26.5 grams of the above product were combined at a temperature below 10 C., and then heated and kept at 75 C. for 8 hours,

cooled to 25 C., and drowned in a mixture of ice and washed and dried.

Example I V HO NH:

--S OgNHg S O NH:

As in Example I, grams of 8-amino-1-naphthol-5,7- disulfonic acid was phosgenated. 34.5 grams of this product was converted to the sulfonyl chloride as in Example I.

The sulfonyl chloride paste was added to 58 grams of ammonium hydroxide (29.4% soln.) at room temperature. It was maintained at this temperature for about 4 hours and filtered. a

The paste was added to a solution of 200 cc; of water and 50 cc. 30% by weight of sodium hydroxide solution, heated to 95100 C. for 1 hour, cooled to 70 C. and diluted to 500 cc. Hydrochloric acid (20 B6.) was added to a pH of 7. It was cooled to around 5 C., filtered,

washed and dried.

Example V HCI) IlqHz a )2N'0zS S zN 3):

As in Example I, 160 grams of 8-amino-1-naphthol-3,5- disulfonic acid was phosgenated. 34.5 grams of this product was converted to the sulfonyl chloride, also as in Example I.

The sulfonyl chloride paste was added to 120 grams of dimethyl amine (35% aqueous solution) at a temperature below 15 C. It was maintained at this temperature for 4 hours and filtered.

The paste was added to a solution of 200 cc. water and 50 cc. 30% by weight of sodium hydroxide solution, heated to 95-100 C. for 1 hour, cooled to 70 C. and diluted to 500 cc. 40 grams of sodium bicarbonate was added. It was cooled to about 5 C., filtered, washed neutral and dried.

Example VI HO NH:

Example I was again repeated through the formation of the sulfonyl chloride.

The paste was added to a solution of 99.5 grams of p-toluidine dissolved in 500 cc. chlorobenzene at room temperature. It was stirred for about 4 hours. 50 grams of soda ash was added, and the charge steam distilled until all solvent was removed. The resulting slurry was cooled, reduced to a pH of 7 with hydrochloric acid 20 B., cooled to about 5 C., filtered, washed and dried,-

I claim:

1. The process of preparing 8-amino-1-naphtholsulfon amides which comprises treating an aqueous alkaline slurry of S-amino-l-naphthol containing from 1 to 2 sulfonic acid groups with phosgene at a temperature of O20 C., treating the intermediary phosgenated product with chlorosulfonic acid, heating the treated mixture at -110" C. for a period of time suificient to yield the corresponding sulfonwl chloride intermediate, drowning the latter intermediate in ice Water, followed by filtering and treating with an amine selected from the class consisting of ammonia and unsubstituted liquid mono and di-alkyl, aryl, aralkyl and cycloalkyl amines and morpholine, piperidine and pyrrolidine, and recovering the 8- am-ino-l-naphtholsulfonamide.

2. The process according to claim 1 wherein the 8- amino-l-naphthol is 8aminol-naphthol-3,6-disulfonic acid.

3. The process according to claim 1 wherein the 8- amino-l-naphthol is 8-amino-1-naphthol-5-sulfonic acid.

4. The process according to claim 1 wherein the 8- amino-l-naphthol is S-amino-1-naphthol-5,7-disulfonic acid.

5. The process according to claim 1 wherein the 8- amino-l-naphthol is 8-amino-1naphthol-3,5-disulfonic acid.

References Cited in the file of this patent UNITED STATES PATENTS 2,520,917 Dickey et a1. Sept. 5, 1950 FOREIGN PATENTS.

667,772 Great Britain Mar. 5, 1952 OTHER REFERENCES Einhorn et 211.: Ber., p. 3647, vol. 35 (1902). Kitamura: Chem. Abs., p. 3434, vol. 30 (1936). 

1. THE PROCESS OF PREPARING 8-AMINO-1-NAPNTHOLSULFONAMIDES WHICH COMPRISES TREATING AN AQUEOUS ALKALINE SLURRY OF 8-AMINO-2-NAPHTHOL CONTAINING FROM 1 TO 2 SULFONIC ACID FROUP WITH PHOSGENE AT A TEMPERATURE OF 0-20* C. TREATING THE INTERMEDIARY PHOSGENATED PRODUCT WITH CHLOROSULFONIC ACID, HEATING THE TREATED MIXTURE AT 70-110* C. FOR A PERIOD OF TIME SUFFICIENT TO YIELD THE CORRESPONDING SULFONYL CHLORIDE INTERMEDIATE, DROWNING THE LATTER INTERMEIDATE IN ICE WATER, FOLLOWED BY FILTERING AND TREATING WITH AN AMIDE SELECTED FROM THE CLASS CONSISTING OF AMMONIA AND UNSUBSTITUTED LIQUID MONO-AND DI-ALKYL, ARYL, ARALKYL ABD CYCLOALKYL AMINES AND MORPHOLINE, PIPERIDINE AND PYRROLIDINE, AND RECOVERING THE 8AMINO-1-NAPHTHOLSUFONAMIDE. 